DatabasePDO.class.php

<?php

class DatabasePDO extends PDO
{
    protected static $singleton = null;

    public static function singleton()
    {
        if (is_null(static::$singleton)) {
            static::$singleton = new static();
        }

        return static::$singleton;
    }

    public function __construct()
    {
        // $db = new PDO("sqlite::memory");

        $connectionString = "mysql:host=". DB_HOST;

        if (defined('DB_PORT')) {
            $connectionString .= ";port=". DB_PORT;
        }

        $connectionString .= ";dbname=" . DB_DATABASE;
        $connectionString .= ";charset=utf8";

        parent::__construct($connectionString, DB_USERNAME, DB_PASSWORD);
        $this->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    }
}